1. Field of the Invention
This invention relates to a method and apparatus for confirming or controlling the presence of composition variation or the variation course by analyzing automatically and frequently the time-dependent variation of the composition of a fluid, which involves a time-dependent variation of composition, in various reactors and stills.
2. Background Art
Continuous detection or analysis of the composition of liquid components, for example, in a reactor for conducting a variety of chemical reactions or in a distillation column, has been practiced to data in a few cases under specific conditions. In one of the cases, for instance, there exists a sensor capable of direct detection of the characters specific to the properties of an intended component, while in another, a specific means of instrumental analysis is available which can analyze reaction liquids successively in a short period of time without any prior treatment, like gas chromatography and liquid chromatography.
However, these available detection procedures are actually limited to only a few choices among a number of analytical techniques. One of the reasons is that the sensor as described above has not been developed yet, or that the troublesome pre- and post-treatments of samples required for the adequate operation of a sensor make it difficult to automate these treatments and hence always need manual help, thus failing in frequent and continuous detection. The second reason is that the analytical method itself is complicated, though established as a procedure for analysts, so that the analytical instrument for effecting the method has not been developed.
In various reactions, particularly in batch reactions, on the other hand, it is desired to detect frequently the time-dependent variation of the reaction rate and thereby to confirm the progress of the reaction. Further, it has become necessary to improve the quality and function of the product by allowing the reaction to follow its predetermined or intended desirable reaction course, if possible. In most of these methods, raw materials necessary for the reaction are fed into the reactor collectively at the beginning or only a part of the raw materials is charged continuously or intermittently during the reaction, but various reaction conditions are maintained constant. In some cases, analytical operations are carried out during a reaction. However, they are only such that the temperature and pressure of the reaction, the revolution speed of a stirrer, etc., are simply caused to vary in accordance with a schedule, or the reaction conditions are controlled according to the data obtained by converting signals from a commercially available sensor through simple processing. For example, the operation procedures are merely to detect the reaction temperature by a temperature sensor to regulate the heating level of a heater or to measure the pH of a liquid by means of a glass electrode so as to add a pH-controlling solution. The cases to which these procedures are applicable are limited entirely to those where adequate detection sensors are available and, in addition, a monitoring system, by which signals are obtained at required intervals, can be employed. In other words, due to the limitation to the monitoring system which does not require various pre- and post-treatments for an object to be treated, the reaction, which is to be conducted under the conditions adjusted according to the momentarily changing properties of a material in the reactor, had to be continued under the conditions estimated based on the past experience and the like.
Further, when analysis has to be carried out during a reaction, 1) sampling, 2) pretreatment, 3) analysis, 4) post-treatment, etc., are generally repeated generally manually. In industrial production sites, research laboratories, etc., however, it is troublesome from the standpoint of manpower to continue the daily analysis repeated at intervals of a few minutes to a few hours, and also errors are unavoidably generated by analytical personnel.
As an auxiliary means to solve these problems, so-called automatic analytical apparatus have anyhow become commercially available in recent years. For example, when set with a sample (to be exact, a receptacle containing a sample liquid having undergone a pretreatment), an automatic titration apparatus starts titration, determines the end point, and prints out the results. Generally, in the apparatus of this kind, a turntable or the like is provided as an adjunct for analyzing a large number of samples in order. However, such mechanism can only analyze, say, eight samples having undergone a pretreatment and setting, and in addition the post-treatment will also have to be dependent on manpower. Moreover, with this apparatus, it is absolutely impossible to feed back the analytical results to the operation conditions of the reactor under reaction. Furthermore, in a batch operation, the amount of the substance to be analyzed varies with the progress of the operation, and therefore the amounts of the substance and analytical reagents to obtain proper analytical results and accuracy are, in general, not irrelevant to the progress of the operation. Hence, the concentration of the substance to be analyzed in the system can vary significantly from the beginning to the end of the reaction. However, in such a case as the above-described samples, there is a serious problem that since the samples taken previously and pretreated are to be arranged on a turntable, it is substantially impossible to take samples successively and regulatively in accordance with the progress of the operation in such a way that the amounts of the samples are optimized with regard to analytical accuracy. These circumstances are exactly applicable to the aforesaid instrumental analytical apparatus including gas chromatography and liquid chromatography.
The present inventors have made intensive investigation into a method whereby tracing of the time-dependent variation of a fluid composition is made possible through high frequency analyses by automating the analytical procedures as described above, which have not been very usable, leading to completion of the present invention.